diff --git a/CHANGELOG.md b/CHANGELOG.md
index c0d569a..a79fe7e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,7 +14,6 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
   - generichash
   - hash
   - kx
-  - public
   - pwhash
   - randombytes
   - secret
diff --git a/c_src/public.c b/c_src/public.c
index cc1925b..3c47bcf 100644
--- a/c_src/public.c
+++ b/c_src/public.c
@@ -255,7 +255,9 @@ ERL_NIF_TERM enacl_crypto_box_seal(ErlNifEnv *env, int argc,
 
   crypto_box_seal(ciphertext.data, msg.data, msg.size, key.data);
 
-  return enif_make_binary(env, &ciphertext);
+  ERL_NIF_TERM ret_ok = enif_make_atom(env, ATOM_OK);
+  ERL_NIF_TERM ret_bin = enif_make_binary(env, &ciphertext);
+  return enif_make_tuple2(env, ret_ok, ret_bin);
 }
 
 ERL_NIF_TERM enacl_crypto_box_seal_open(ErlNifEnv *env, int argc,
@@ -283,5 +285,8 @@ ERL_NIF_TERM enacl_crypto_box_seal_open(ErlNifEnv *env, int argc,
     return enacl_error_tuple(env, "failed_verification");
   }
 
-  return enif_make_binary(env, &msg);
+  ERL_NIF_TERM ret_ok = enif_make_atom(env, ATOM_OK);
+  ERL_NIF_TERM ret_bin = enif_make_binary(env, &msg);
+
+  return enif_make_tuple2(env, ret_ok, ret_bin);
 }
diff --git a/eqc_test/enacl_eqc.erl b/eqc_test/enacl_eqc.erl
index 2a1a9f0..6a43dcf 100644
--- a/eqc_test/enacl_eqc.erl
+++ b/eqc_test/enacl_eqc.erl
@@ -431,7 +431,7 @@ prop_seal_box_failure_integrity() ->
       begin
          case v_iodata(Msg) andalso keypair_valid(PK1, SK1) of
            true ->
-             CT = enacl:box_seal(Msg, PK1),
+             {ok, CT} = enacl:box_seal(Msg, PK1),
              Err = enacl:box_seal_open([<<"x">>, CT], PK1, SK1),
              equals(Err, {error, failed_verification});
            false ->
@@ -450,7 +450,7 @@ prop_seal_box_correct() ->
      begin
          case v_iodata(Msg) andalso keypair_valid(PK1, SK1) of
              true ->
-                 SealedCipherText = enacl:box_seal(Msg, PK1),
+                 {ok, SealedCipherText} = enacl:box_seal(Msg, PK1),
                  {ok, DecodedMsg} = enacl:box_seal_open(SealedCipherText, PK1, SK1),
                  equals(iolist_to_binary(Msg), DecodedMsg);
              false ->
diff --git a/src/enacl.erl b/src/enacl.erl
index 5a2375a..037bafb 100644
--- a/src/enacl.erl
+++ b/src/enacl.erl
@@ -685,7 +685,7 @@ box_secret_key_bytes() ->
 %% keypair and then uses `box'. Ephemeral public key will sent to other party. Returns the
 %% enciphered message `SealedCipherText' which includes ephemeral public key at head.
 %% @end
--spec box_seal(Msg, PK) -> SealedCipherText
+-spec box_seal(Msg, PK) -> {ok, SealedCipherText} | {error, term()}
     when
       Msg :: iodata(),
       PK :: binary(),
@@ -706,10 +706,7 @@ box_seal(Msg, PK) ->
       SK :: binary(),
       Msg :: binary().
 box_seal_open(SealedCipherText, PK, SK) ->
-    case enacl_nif:crypto_box_seal_open(SealedCipherText, PK, SK) of
-        {error, Err} -> {error, Err};
-        Bin when is_binary(Bin) -> {ok, Bin}
-    end.
+    enacl_nif:crypto_box_seal_open(SealedCipherText, PK, SK).
 
 %% @doc secretbox/3 encrypts a message with a key
 %%